In the field of ophthalmology, various kinds of apparatuses are used for imaging a subject's eye. In recent years, optical coherence tomography apparatuses capable of acquiring cross sectional images and three dimensional images of a fundus and of an anterior segment have been attracting attention.
In the optical coherence tomography apparatuses, various scan patterns are used according to the objects to be imaged, the targets of analysis, or the like. Examples of scan patterns include line scan (e.g., horizontal scan, vertical scan, etc.), cross scan, radial scan, concentric scan, three dimensional scan, and the like.
Furthermore, a scan patterns that is a combination of two or more scan patterns can also be employed. For example, there is a scan pattern (referred to as multi-line cross scan) in which a group of horizontal scan lines parallel to each other and a group of vertical scan lines parallel to each other are placed so as to be perpendicular to each other in the vicinity of the center positions of the both groups of scan lines. In practice, a scan pattern called five line cross scan is applied which is a combination of five horizontal scan lines and five vertical scan lines.
A user sets a scan position as well as selecting a scan pattern. For example, the user selects a five line cross scan as a scan pattern and sets a scan position such that an intersection area of the five line cross scan is placed at a site of interest (e.g., macula or the like) of the subject's eye. The setting of the scanning position is performed by moving a mark (i.e., image) representing a scan pattern displayed on an observation image (i.e., moving image) of the subject's eye.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2014-155875
With the conventional ophthalmic imaging apparatus, as described above, in order to observe the site of interest and peripheral sites thereof, the scan pattern (i.e., the mark) is moved while maintaining the shape of the selected scan pattern.
However, with the conventional ophthalmic imaging apparatus, the scan pattern can be moved only within a scannable area, which is limited by hardware constraints or the like, and thus it is sometimes impossible to place the intersection area of the scan patterns at a desired position within the scannable area. For example, when it is desired to observe a site of interest located in the vicinity of the boundary of the scannable area and peripheral sites of the site of interest, it is impossible to set the scan position at the site of interest or in the vicinity thereof and thus to observe the site of interest. In this case, the site of interest is required to move in the observation image by moving a fixation target or the like, and the degree of freedom of scanning decreases.